Reference: https://meta.stackexchange.com/questions/331378/why-is-there-a-clustering-of-answers-at-full-half-hours-between-answers
Q&A for Ubuntu users and developers
WITH timeSeparation AS ( SELECT q.Id AS qstId , c.* FROM Posts q CROSS APPLY ( SELECT a.Id AS postId , a.CreationDate AS postDate , minsAfter = DATEDIFF (mi, ISNULL (LAG (a.CreationDate) OVER (ORDER BY a.CreationDate), q.CreationDate), a.CreationDate) FROM Posts a WHERE a.PostTypeId = 2 AND a.ParentId = q.Id ) c WHERE q.PostTypeId = 1 AND q.AnswerCount > 0 ) SELECT ts.minsAfter , [Number of Answers with the given delay] = COUNT (ts.postId) FROM timeSeparation ts WHERE ts.minsAfter < 301 -- otherwise long tail swamps out plot AND ts.minsAfter >= 0 -- Answers can be older than questions if they were merged in. Discard those. GROUP BY ts.minsAfter ORDER BY ts.minsAfter